1. Finely grate the rind from the lemons, making sure you don’t grate off any of the bitter white pith. Place it in a heatproof jug with the sugar.

2. Pour over the water and stir until the sugar has dissolved.

3. Cut the lemons in half, and squeeze the juice from the lemons (try using a fork to get the last drops out). Strain through a sieve into the jug. Taste, adding a little more sugar if you like. Allow to cool then chill. Serve with ice.